"I'm really excited. I'm happy. I can't wait to be a dad," Lopez tells PEOPLE.
Lopez, 36, and his girlfriend, actress Courtney Mazza, 28, met in 2008 when Lopez starred in A Chorus Line on Broadway.
So is the former Dancing with the Stars competitor – and longtime playboy – ready for diaper duty?
"Of course," Lopez says. "I grew up in a large family. I'm fired up! I don't know what we're having. I'm going to wait to see [the baby's gender] so it will be a surprise."
Lopez is also the host of MTV's America's Best Dance Crew.